How can i find my mothers great grandfather?

Question:

How can i find my mothers great grandfather?

he served in WW1 and WW2

Best Answer - Chosen by Asker: This link
http://www.archives.gov/
will let you write for his service records if he served the USA. France, Germany, Italy, Russia, England, Scotland, Japan, Canada, NZ and Australia have similar sites but I don't know the URL.

If he died in WWII and was a commonwealth soldier, the CommonWealth Graves Commission will probably have a record for him.

If by "Find" you mean find his name, your mother's grandparent's birth certificate or wedding license may list it.

I hope this helps. Your question wasn't very clear.