To knock down any barriers you have and let God into your soul.
Submitting to God is putting aside our pride and selfish desires to do what we want to do in our own flesh and trusting God to do what is best in whatever situation. It's telling Him that we are going to trust Him no matter what, even if we don't see answers right away or receiving an answer we may not like. We have to trust that God does know best, He knows the future.
It's wanting His will more than our own. It can take awhile to get to this point but the more we get to know Him, the more we will love Him and want to please Him.
To surrender all to Him; so you can do the work He has for you to do. This work maybe helping others; may have you walk where you never thought you could ever go. As another poster said.. you dedicate your life back to Him. Meaning you will do His will in your life not your own. You will not want to do your own will but listen and do His.
Surrender all to Him!!