A very common chord progression 1-4-5
Some chords just sound great together and many, many songs use this one. A very common and great chord progression to jam to or experiment with is the I IV V (1-4-5) chord progression. So for example if you started in the key of A (A=1 B=2 C=4 D=4 E=5 F=6 G=7 , counting from A, A would be the 1, D would be the 4 and E would be the 5...so you could jam with an A then D then E and improvise all sorts of great songs. Below is the 1-4-5 in each key to make it easy to experiment with!
Below are the basic "Open" Chords...the top row is Major and the second row is the minor and the bottom row is the 7th. Each has it's own flavor...The major chords are brighter and cheerier while the minor chords have a darker, sadder sound. Learning these open chords and their variations is a good place to start.