Vows aren't a scary thing. And if they seem scary to you, that's why I'm here to help.
Remember; vows are exchanged between you and your partner. Having every else there is a bonus, but don't write them to entertain the audience. They should be meaningful and heartfelt.
Start with a memory about your partner. When did you know you wanted to marry them? What is a significant moment in your relationship?
From there, move onto why you want to marry your partner. What is something cute/annoying/enchanting they do? Why do you love them? Why will you always love them?
And finally, end with a vision to the future. What do you see you both doing in 5 years time? What will change when you are married? What do you see improving?
See! Not so scary after all. There's plenty of examples out there on the inter webs, but remember to keep your vows all about you. It's like picking a good bunch of grapes at the supermarket; it's okay to have a taster, but don't eat the whole bunch.
Just remember, there are some legal vows that you MUST say. Can't wiggle out of those ones.