My friend told me if you are a girl you have to worship a goddess and if you are a boy you have to worship a god. I was almost absolutely certain this was a lie. I just need reassurance and what is it like to choose a path and work with a god/goddess?
You can worship anyone you feel drawn to or calls to you regardless of their perceived gender. You also don't have to worship anyone if you don't want to.
It depends on the person really, I have an altar for my deity, leave offerings for her and may ask for her assistance during ritual from time to time, but that is just what I find works best with my deity, others will be different.
So ive got a deity in mind and i was trying to offer something and i realized: my mom does NOT let me burn stuff. besides, i do not like burning anything! Is there any way to make offerings without burning it? Oh yeah, what are sone examples of offerings?
Before jumping into deities, why not do some of your own research on them. Forming a relationship with a deity isn't something that you enter into randomly or on a whim, same goes for the deity/s you choose to work with, often it takes years for your deity to call to you, or you can bond with one that you feel drawn to, but it all takes time and isn't instant. .
Offerings differ depending on the deity, some prefer items, flowers, some incense, liquids, etc. It all depends on your deity/s and also your relationships with them, some deities will ask you for specific offerings while others you can be more flexible with, others may not want physical items at all. These things develop with time and work to discover, asking a forum with people who work with different deities than you isn't the best way to undergo finding information regarding your personal relationship with your deity/s.
It's not something you decide to do one day without research on your particular deity and information regarding deity worship.