How to increase erection n penis size?

Not possible. Do not believe any of the fictious claims for penile enlargement. Penile size can only be acheived before puberty. No herbal or hormonal treatments work. Operations to enlarge the penis do not work unless you have penile chordee (downard curvature of penis) which needs correcting. Surgery to divide the suspensory ligament of the penis or fat injections can all harm you and do not work.