Having the AP engaged, even heading, during your take off roll is asking for trouble!
Have you checked the tutorial on the app for take off and landing? It has a C172 that shows you the basics.
If you want to try a jet suggest that you first start off in say the B737-700 as a good starter.
*Try first in SOLO mode, set wind to 0 and temp to about 15-20 Deg C.
*When you first spawn (on a runway of your choice) first put your brakes on.
*Set your weight and balance to ‘normal’ (make sure your MLW is green)
*Next set your height section in the AP is set to about 3000ft
*Trim = 0
*Spoilers = OFF
*Flaps = 15
*Then release your brakes, advance your throttle first to about 50% then when you are rolling in a nice straight line increase throttle to about 85% for take off.
*When you reach about 150kts slowly pull the nose up to 5 degrees (first line on the HUD), when you are clear of the ground you can increase the rate of climb to the second line on the HUD (10 degrees), then select gear up.
*Now you can put your Auto pilot on in stages. First put heading on then also height (make sure the VS is between 2500 to 3000), leave the speed until you reach about 200kts.
*once above 1000ft in height you can slowly bring the flaps up in stages and at the same time increase your speed to 250kts. By the time you have reached 3000ft you should be in a ‘clean’ state, ie al flaps in, gear up and climbing at 250kts.
*Then you can look to change course and enter the pattern for some touch and gos!
*When you have some experience with no weather, slowly start adding in some wind so you can see how it effects your take-off and landings, soon you will be ready to tackle live!