You Can Do It!
Keeping you cat’s nails trimmed means they are less likely to want to scratch something other than their scratching post.
If this is your first time, start without the clippers, gently pressing on the paw so you get the knack of extending the nails. It also gets kitty used to you handling his/her paws.
Cut off only the very tips of the nails. You must avoid cutting into the quick of the nail. (See the Petsmaster article linked below for an image of the quick). You do not have to do all the nails at once. Do what you can before your cat has had enough and then continue another time.
Some cats are more tolerant then others when it comes to nail trims but doing it while the cat is relaxed and maybe even sleepy helps.
There are all kinds of clippers for nails but this type is inexpensive and does the job. In the Vancouver Vet video, he prefers using human nail clippers. Watch a video to understand the process or you could ask your vet or show you how to do it.