9, 11 and 13 chords are all considered dominant chords, although in blues and gospel, the 9 and 13 are often used on tonic chords.
The "11" is often omitted on a 13th chord, because it clashed with the "third".
The "11" chord is usually considered a sus chord - ie- G11 is a Gsus chord, and can be played as an "F" triad over a "G" bass: F/G. (Used a lot in Motown!)
An easy way to make a "13" chord is to play the basic dominant chord in the left hand, and add a minor triad a minor third lower. For example: G13 is G7 in the left hand, and E minor triad in the right hand (E,G,B) the "E" being the thirteenth.
All the best!