I have a roofing company lined up. So my insurer sent me a check. I have a mortgage on the house.  What is my next steps being new to all of this?

Argh, I had to do this before.

Assuming check is paid to you and mortgage company.

Call your mortgage company, they will connect you with the right dept, and they should give you instructions.

You will have to send it to them with roofing quote and they will cosign it and send it back.

Legit roofers are familiar with this and shouldn't have an issue as long as you show them check or photo of it.
My roofer scheduled and did the work while waiting for the check to come back.

I just did this from Harvey, I didn't do shit with the mortgage company.

Got my check from TWIA(in my name), cashed it, showed my roofer what TWIA gave me, they worked with TWIA and got me another $400 check(in my name) I cashed that.
Roofer did the job under quote so I actually saved about $400 on my deductible. I gave the roofer their check(from my savings account), a couple months later I got all the TWIA paperwork required.

At no point was there anything to do with my mortage company.

Luckily for me, between TWIA and the roofing contractor, they new what was going on so I didn't have to stress too much.

In some states, any claim over $10k has to be managed through the mortgage company. I have had this experience twice - one with a monster credit union and I was warned it would suck. I fedexed them a packet of paperwork with a table of contents, and they processed it and deposited the check same-day. With a smaller mortgage company, I showed up with the check, a VP countersigned and I was on my way in less than 15 minutes. Bottom line, they want to make sure their services are good AND their investment is protected, so you may have to prove that you are doing or have done the work.

-shooter