You need to do at least a couple of things
1. Get lots of people looking at your web page
2. Get the people visiting your web page to buy. If you get 1% to buy, that's a good start (which means you have to get 100 targeted people to make even one sale).
Do you know how many people are viewing your page?
Install some kind of tracker/counter to find out. You can find some athttp://www.hits4me.com/rem_counter.php
Sitemeter is reasonable and has a free version.
Then look at getting more people to view it:
Pay Per Click Search Engines -http://www.marketingblast.com/res_ppc.php
Swap links with other sites
More ideas at
2. I do not think your sales letter will convert very well
If you were reading it, would you buy?
Tell people what is in for them. What will they learn? How will they benefit?
What do they need to read it? (I imagine most people in the market for this book would be newbies, but I can't tell as the sales info is so brief)
Why should they trust you?
What if they don't like it? (A guarantee of some sort)?
Maybe show an extract (to build confidence)
#3 You could also consider follow-up
Start a newsletter or autoresponder. Info atwww.ezineblast.com
You could send people an extract or computer tip, opt-in email, regularly, each time reminding them of your eBook
You might want to consider selling thru ClickBank rather than PayPal. Set a high affiliate %, and you will probably get some affiliates promoting.
Look at #1 to #3 first before doing this