SGear is great and has a pretty long free trial that comes with it. It also works as a standalone.
Usually, with whatever daw you are using, if you open the program folder in Windows, you will see a VST folder, where all the plugs for your DAW are stored. If you open the program folder for S-Gear after it is installed, you will see a .dll file. If you drag and drop that into the DAW’s plug in folder and have the DAW search for it, it will then show up like a VST instrument.
If all you want to do is jam, the standalone will be on your desktop, you just open it up and pick a preset and start spankin’ the plank. If you want to make a preset, you select an amp, pick a mic and cabinet, pick effects, and save it if you like it. It actually feels like you are playing through a real amp. Try it out and see what you think.