Hoppers make sure you check with your parents first. Most door frame architraves are strong enough to take your weight. Some may need a couple more panel pins put in just to give them a bit more strength.
Using just your fingertips try and pull yourself up, start with one or two and work your way up. The younger you are the easier it will be. It takes a lot of finger strength to do a pull up on architrave. If you’re not strong enough put your feet in front of you with your arms fully extended and pull up as far as you can. Some of your body weight will be in your legs and that is okay. As you get stronger you’ll be able to lift your legs slightly off the ground. Or just try and hang on the architrave and lift your feet off the ground. Take care and have fun.