How can I project my sales in my business plan? knowing that I didn't yet start the business?

the product will be sold only by Direct marketing and salespeople for the time being at least.

Let me put this better; the product is an electronic piece, a bit expensive thus, target customers are the business society who will benifte the most from it.
there is only one side of competetion in the market, one company, and we could simlpy get better services and much better and conveniet produts/prices.
still the problem is that I can't go right now for public advertising, So I'm heading for sales forces directed to the segmented market and given a target to achiev.

Any projection, even in a known market, involves assumptions. In your case you will have to make a few more, but that is OK. The key is that you clearly state what your assumptions are. Then as you gain knowledge of your market and your customers, you can replace assumptions with data, or at least educated assumptions.

I would suggest starting with some identification of what you consider your market. Quantify the market (how many companies, how much do they spend on similar products or services, etc.) This type of information should be pretty available unless your product is very obscure or new. Then, once you know the size of the market, identify and quantify your competition. How much are they selling to your customers? How much do you expect their market share to change? Calculate some measure of market strength or expansion.

Subtract your competition from the market capacity and that is your potential capacity. I hope this helps!

Is there a competive product? How much does it sell for? How widely is it distributed? How many units do they sell a week/month/year? Multiply that times the number of other products that fit in your category. What % of that total market do you expect to acquire? That is your sales projection.
Don't count on direct marketing or having a salesforce as providing an extra lift. Both are the cost of entry in sales and marketing.

Good luck.

RESEARCH RESEARCH RESEARCH

Namely, research your competitors, try to guess how much market share you can steal.

I support the reply by Joe D. although you can still work into deeper details per sku, knowing where to place that. For example; talking about consumer products, you should specify how many outlets you are targeting, and what areas on the shelves can you get for your products/sku.

Then calculate how many facings you may have in each outlet and in depth how many units can you display. Take into consideration that you should have some quantity of each item in the outlet stores for immediate supply when the shelf runs short.

Multiply that calculation by the number of outlets, adjust according to the size of each outlet, then you would have a full calculation for a month of supply in all outlets. That would vary from month to month according to seasonalities.

Draw your figures into Excel tables and make the program count those for you, at the end you would have a full projection for the year.

Now upon that calculation you may assign your targets per month per area and give those targets for your sales force to achieve.

This scope of work we are implementing for our products in the Arabian Gulf and having good results. Each salesman has his area, number of skus and target to achieve.

Get your company website and make sure all of your products are listed inside it. The webhosting or domain are available here: http://www.website.ws/powercontrol

I am projecting my business plan too and u can refer to my very very simple website as a sample -> http://www.silverroad.ws