Quarinteen,

Your printer is using a modified version of the Marlin firmware. There is an auto home function in the menu. As far as leveling the bed I would use a piece of paper to do so.

The gcode to home your printer from Repetier is g28. Most slicing software places this as the first bit of code before it starts printing. Try the Cura option for printing. Its drag and drop of .stl files and then copy them to a SD card and print from there for your first few until you get a better grasp of 3d printing.

Move the nozzle to the front left of the bed and raise/lower the bed with the thumb screw from underneath. repeat this process for all 4 corners. you will want the piece of paper to slide through with a little force.

Take that level and move it away from the printer. you won't need it for 3d printing. below is a 4-minute video to show the same thing I said above.
https://www.youtube.com/watch?v=L6GJWHwrTmY

I hope this helps.

These are my opions and they may not reflect all viewers of 3dprintboard.