nose riding

I've searched the forum but haven't found an answer to my specific problem. I'm new to longboarding and I've been out on my board about 11 times now. About 2 weeks ago (before I ended up in hospital!) I was trying to noseride. I know it's going to take YEARS to get it.. but this thing has been bugging me (I've had alot of time to think about it lately!)
I was wobbling all over trying to walk up the board and when I did make it to about 1-2 feet from the end the whole board started sinking under the water. I did this several times and every time it just kept sinking, so I'd jump off! What am I doing wrong and are there any good instructional "how to" type video's that take you through it step by step?
I was wobbling all over trying to walk up the board and when I did make it to about 1-2 feet from the end the whole board started sinking under the water. I did this several times and every time it just kept sinking, so I'd jump off! What am I doing wrong and are there any good instructional "how to" type video's that take you through it step by step?