Here are some codes I know for making games:
To move an object to the right, you use this code:
if keyboard_check(vk_right)// checking for right key pressing
{
x += 4 //moving to the right by 4 pixels
}
It's pretty simple.

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Another type of moving.
For example, if you have a platform, you could set the hspeed to 3.

hspeed = 3

Not that hard. If you want to learn moar, go here and download the gamemaker and study some of its specs.