Wrap your fingers firmly around your penis and slide your hand up and down.
The most sensitive area is the glans and the rim around it.
If you are not circumcised the glans may be too sensitive to touch directly. This is solved by moving the foreskin up and down, stimulating the glans indirectly.
When your excitement increases it can feel good to speed up, moving your hand up and down faster.
Try to use some saliva or a lubricant. Some guys like to masturbate dry, while others like it to be slippery. Discover what you like best.
If you are in your early teens and never had an ejaculation yet, you can still masturbate and come to orgasm. Ejaculating and climaxing are two different things.