Getting started with QGIS

Open QGIS 2.18 Desktop with GRASS 7.4 by clicking the program icon.
Look around the screen to identify the canvas where active layers will be shown as map; Functional menus (Files, Layers, Settings, etc.); Functional tabs (Zoom, Identify Features, Select Features, etc.), Layers Panel, and Browser Panel.
Go to Plugins-Manage and Install Plugins. Install a few plugins such as Road graph, and Copy Canvas to Clipboard.
On the lower right corner the projection is shown. The coordinates can be seen at the bottom of the window. The default is EPSG: 4326.
To change the projection of the canvas, one way is to go to Project-Project Properties-CRS. If you know what projection you need, type the key word in the Filter window. Otherwise, go to Coordinate reference systems of the world. Expand the Projected coordinate systems and go down the list to find what you need.
Suppose we need WGS 84 / UTM zone 16N (appropriate for Illinois). First try to use Filter. Type WGS 84 / UTM zone 16N in Filter. If nothing comes up within Coordinate reference systems of the world, go to expand the Projected coordinate systems list. Go down the list and look for WGS 84 / UTM zone 16N. When you find it, select it, OK. Look at the lower right corner and the coordinates, you should see changes.

Download the shapefile State_IL. This is a zipped file and you need to download it to your personal flush drive and unzip it. Every single file from it should be placed within the same folder.
Within QGIS, go to Layer-Add Layer-Add Vector Layer. Use Browse to navigate to your folder to select State_IL.shp. Open. Open. Once in, select and right click it. Go to Open attribute table to examine what fields or variables are in the layer. Close the table.
Select and right click the layer, go to Properties-Style. Select Graduated. At Column, select POPDENSITY. At Color, choose OrRd. At Mode, choose Quantile. At Classes, you can change the number of classes you want to display (like 7). Click Classify. OK. You should see a map.
Try to use a few tools such as Zoom in, Zoom out, Pan, Identify Features, etc. These are all similar to another other GIS programs.

Now click Select Features. Make sure the layer is active. Click Madison County, then push down Shift key, and select St. Clair County. The two counties should be highlighted. Go to Layer-Save As.
In the dialogue window, select ESRI Shapefile format. Use Brower to fine your flush drive. Type a name such as Two_counties. Save. Still within the dialogue window, select Save only selected features. At CRS, make sure it is EPSG: 32616, WGS 84/UTM zone 16 N. If not, click the button on the right end to choose it from the list. OK. This is an important way to define the projection of a particular layer.
Right click State_IL, select Remove.

Go to Project-Save As. Navigate to your folder to save the project as Intro. Save.