Dont Worry Cass i couldnt change a tyre for ages i am a Mechanical Ignorumus, but i got inspired to learn and im slowly improving now tyre changing is easy onece you get the hang of it, have you got all the tools you need?
Tyre changing levers (i have plastic ones they clip together and they are good)
Tyre Repair kit
Also you could have a spare tube along to get it done even quicker and fix the damaged tube later at home or so.
Also iv found Glue on paches which you applie glue on are the best , (There are now self adheasive patches which are like a sticker) self adheasives are not too good and are not cheap.
Practice changing your tyre before you get a flat (which i did not do youw) Just takes some practice and it will then be easy
especialy if your as lucky as me i one got 2 flat tyres at once yeh. ;D