Squeeky Wheel!!

Sophia has a squeeky rear wheel- and I just can't figure it out. Something is rubbing against the tire .... but what? And here lies one of my big fears about owning a bike - although I suppose that I had the same fears about owning a car .... which is: I am NOT mechanically inclined, and I honestly don't have any desire to change that. However, what do I need to know how to do? It seems silly to take it back to the bike shop for a little squeek -- but I feel even sillier with the squeek - as it is sort of loud!! So - what are the things that I need to know how to do? I have changed a flat before and I am certain that I will be able to change one again. But - what else? I suppose I should do a bit of research on what are the absolute basics of bike repair/maintenance that I need to know.

On another note --- I couldn't find the bike helmet that I want in my size at REI. It turns out that I have a very medium sized head - hopefully that says nothing about what's inside!! ;) So - still searching for the perfect helmet to complete my chic look.

I am also searching for the perfect bag to take on social events. If I am biking - I would like something big enough to hold a pair of platform sandles -- but that doesn't look "industrial" like the backpack I have for more utilitarian trips. Not as easy as I thought ....