There are many sites to help you learn to play piano. I think you can locate them yourself, but I can get you started enough to learn some basics.

If you know the notes on the piano keyboard C D E F G A B C with the black notes being the sharps and flats(one half step higher is sharp one half step lower is flat) and also the singing scale Do Re Mi Fa So La Ti Do, with this knowledge you can begin to learn to play. The first Do is #1 or a 1st, Re is #2 or a 2nd and so on. Since you know the notes select one and put it as your first Do. Then from that Do find each note representing the remainder of the scale. A 1st, 3rd and a 5th will always be a 3 note chord. For example in the key of C, Do or the low C is the 1st, Mi or E is the 3rd, So or G is the 5th. Play this Do, Mi, and So or 1st, 3rd and 5th at the same time and you have built a C triad or 3 note C chord. Remember whatever note you place as the low Do or 1st will be the chord you are building. In order to make a minor of any of these drop your 3rd 1/2 step.

Now that you have that knowledge I don' think it would hurt to get the basics of a rythm and blues progression. Go back to the Do(1) Re(2) Mi(3) Fa(4) So(5) La(6) Ti(7) Do(8). A three chorded R&B progression is the basis of both 8 and 12 bar blues plus seed that grew to most modern music. It is a 1st, 4th, and a 5th.. This is the pattern of many classic songs. I could start to list some but the list would almost surely get crazy.

Let's build a 7th. This will make the music a bit more bluesy. Many times a minor 7th is the real deal. To build the 7th, count up 6 notes from the root note. The next note that can be played whether it is in the scale or not is the 7th. Ex. a C7 would be a C, E, G, & Bb. Even a little funkier is the 9th. A quick way to build a 9th that sounds real good is to drop the root note and put the 7th on the bottom. The traditional method is to drop the root note and add the 9th or 2nd Re. Start with an inside out C7 which would be from low to high G, Bb, C, E. To make the 9th, drop the root note and add the 2nd Re. The C9 would be G, Bb, D, E. You can compare it to the short version which would be Bb, E, G.

This learning is easy to transfer to other instruments. The bass player in "Yesterday's Hooligans" was my first student and now I'm in a band with him.