I work in Houston Texas and need to receive my sons grades

Diane, you have posted your question on a nationwide message board, not your son's school website. You may want to phone the school during normal Monday-Friday business hours, and ask if there is a specific procedure for having grades sent. (Also, it's not clear if you are looking for a single set of semester grades, or if you want daily/weekly updates...teachers may be more resistant to that, unless your child has a formal accommodation plan.)

Diane: While I can't speak specifically for schools in Houston, TX (there may be confidentiality issues related to state laws), I've found that emailing the principal and explaining what I needed and why I needed a something related to my daughter's education has most often been the best starting point. It doesn't always work -- but in those cases, starting out this way, has allowed me to go to the district level when the principal hasn't been helpful.

So, here's what I would do: I would write a formal email (that is to say an email that looks alot like a letter - with a formal salutation etc) and I would say something along the lines of:
Dear Mrs. Principal:
My child is a X grade student in Mrs. Teacher's Name class. I would appreciate her current grades in all subjects so that I may (whatever you need them for). It would be particularly helpful to receive this information emailed to me no later than (10 business days from the date of your email)).

A couple of points: some schools may not want to sent this information to you via email, citing privacy concerns. This may be a battle that you just don't want to fight. If time is of the essence, offer to provide a prepaid overnight express mail or FedEx envelope. Yes, this will cost you money but otherwise you could spend a lot of time arguing the point.
If they still refuse, call the district and ask for assistance.

I thought by doing this process i would get an answer on how i can get my sons grades emailed to me