I remember sitting in new teacher orientation at my district. At least 5 times the mentors said, "If you have any questions or you need help with a student or lesson, talk to a special ed teacher." That's when I knew I was in trouble. I was just as new as everyone else yet I was expected to be able to fix problems for everyone. Chances are, you will be a valuable resource to the rest of your building.
I quickly gathered all the forms that my buildings/district use. Referral to special ed form, RtI referral form, Aide justification form, Parent input forms for the IEPs, the handbook that is sent to parents from the special ed office, and so on. Basically, any form that a co-worker may want to see or need a copy of. All of these forms went in the first tabbed section labeled "Forms".
The next section is labeled IEP Examples. This is where I keep sample IEPs. My co-workers have let me read some of the IEPs they have written. If I really like the management section, I'll copy and paste it into a word document titled Management. I print these sections out as well and put them in this section.
Behavior Plans is another section. Any time I find a behavior plan online that I like, I print it (and save it) and stick it in the binder. I like having a hard copy of these things so I can find them quickly.
Finally, I keep my districts handouts/guides about the special ed department in the last section.
This does not need to be a project that you do all at once. I would set up the binder and as you come across papers, stick them in.