hi would like to add a bit more on as well as practice, practice, practice is the best way but to help you even more try giving yourself a chance, the best way to start off is get as straight as you can to the highlighted markings this will make it easier with only having to make minor adjustments to straighten back up. as you only just started you don't want to be trying to park at massive angles as you will be their for a while, then once you have the hang of it try harder angles.
good luck mate