First make sure that the tabular data you are hoping to work with is saved as a CSV (comma separated values) file and contains X and Y coordinate information for point features that you can successfully represent on a map. If you data is saved in some other file format, like XLSX, open the spreadsheet and save it out as a CSV file. Next verify that your coordinates are stored correctly in two separate columns. Coordinates saved in a spreadsheet are typically coordinates expressed in latitude and longitude, but could also be northings and eastings identifying locations in a specific UTM or state plane coordinate system. If your coordinates are listed together in a single column and are separated by a comma or space (like "30.102, -45.215"), split up your coordinates into two separate columns named X and Y. If you have a large number of rows to process, the Text to Columns tool located under the Data tab can help facilitate this process. When you are splitting up coordinate pair values into separate columns also make sure that have determined whether your coordinates are ordered X,Y or Y,X as your data will not map correctly when loaded into GIS software if these values are mixed up. Once your coordinate fields are named X and Y respectively, each column contains the correct coordinate values (e.g. the X column contains longitude or easting values, the Y column contains latitude or northing values), and your spreadsheet is saved as a CSV you are ready to move on to step 2.
This guide has been developed for QGIS version 3.0 and above so if you are using an older version you will want to visit https://qgis.org to download the latest version of the software before continuing. Once you have QGIS 3.0 or higher installed on your computer, open a new QGIS window. Once QGIS has started up, look in your toolbar area at the top of your application window and click the Open Data Source Manager button.
In the Open Data Source Manager window, look in the left-hand menu bar and click on Delimited Text. Once you've done that, click on the ... button at the top right of the window and browse to the location of the CSV file that contains your coordinate information. Next, click on Geometry Definition to expand those parameter options (if they are not visible already) and then select the fields in your CSV that contains your X and Y coordinates respectively. Be careful when you select these fields - if you accidentally mix these fields up your coordinates will be inverted and your points will show up in the wrong location on Earth. Once you have selected your X and Y coordinate fields, you next need to make sure that the Geometry CRS parameter is set correctly or else your points will not be correctly placed. If your point coordinates are expressed in degrees of latitude and longitude the WGS 84 CRS (EPSG: 4326) is likely the best option. If your coordinates are expressed in meters or feet and are based on a particular State Plane or UTM CRS, make sure you select the correct zone for your points or they will show up displayed in the wrong location. Once you have successfully configured these parameters, click the Add button at the bottom of the window to generate a points layer based on your CSV coordinates and add it to your QGIS project.
You should now see your points displaying correctly in your QGIS project data view. If you are not sure if your points have been placed correctly, add a basemap to provide spatial context. If your points do not seem to be correctly placed, review the instructions in the previous step and try to determine what may have gone wrong. If everything looks correct, you will next likely want to export your point data to a native GIS format to make it easier to manage (if you do not save to a GIS native format, you will have to repeat the steps in this guide each time you want to view your points in QGIS). To save your data in a GIS format, right click on your new point layer's name where it is displayed in your Layers panel, and then select Export > Save Features As... to bring up the Save Vector Layer As... window. In this window, select either GeoPackage or ESRI Shapefile for your format parameter, click the ... button and select a directory and name for your new file, look over the other parameters to see if you need to adjust anything else (usually the default options for the remaining parameters work fine) and then click OK