Ok, Trunks's sword you cannot use it...yet wait for the next beta and then you can, Sensu's you must find them, some maps have them some dont. Now to go ssj, when you see your CF bar go full(make sure that turbo is not on) then press your transform button("Z" is the default) and you should transform, as for evrything else, it should be easy. However if you are having trouble with melee, here is my own lil tutorial, hopefully its easy to follow(keep in mind I am using the default controls when i explain)
1.Left click an enemy when the crosshairs over him are red, then a red box will show up.
2. Hold left click, this will make your character charge at the enemy(otherwise known as "swooping")
3. Since Left click only makes yourcharacter swoop, right click initiates the actual attack, so while holding left click, also hold down right click.
4. If you do that, when you get near the enemy, you'll have successfully(tried) to melee him.