i wanna be part of the human race

I have a big ol favor to ask! Can anyone give me some serious help with my resume & cover letter? Actually my resume is pretty solid (although a look-over never hurts) but I'm applying for a specific job and trying to write a targeted cover letter for it and I've only ever written like 2 cover letters in my life so I'm fairly lost. But I've cobbled together one and would looove if someone could look it over and give me some pointers.

The job is with the Phoenix Public Library and I wants it so baaaaaaaaaaaad! And I feel especially suited to it, because it is a part time assistant position working largely with young kids but also has the 'potential' to work on a position with a program promoting literacy with young kids and I did a year working on early childhood development with AmeriCorps so I feel like I am clearly the most suited to this job hahaha. And I want to articulate that in my cover letter but you know I also don't want it to be too desperate-sounding or whatever. Sigh!

Anyway thanks in advance to anyone that could help :D