If you reply, please keep it simple... I'm always lost in the world of technology.

I wanted to order something and filled out the necessary replies... I even
Started an account. I have ordered from them before. This time, over and
Over and over and over I keep putting in my information incl delivery and
Credit card and it keeps coming back "you already have an account". Anyway
I wrote to the people who hired these webdesigners... they got back to me

They said I have to erase all my cookies. What does that mean... what do I
Lose by doing this?

Although it isn't difficult to erase cookies, it's easier to find the spot on the website where you login instead of starting a new account.
I tend to miss those too, and get frustrated to find out I have an account, but can't get in.
FIND that login box, right on the home page! Click it and then find the place where it will email you with your id and/or password.
Come back if that doesn't work.
I'm not convinced that erasing cookies will help in this case anyway.

If you want to tell us the site, we can try it out.

Typically the companies do not want you to start another account, just like AMHD. In fact, as you are finding out, they will not allow you to process a purchase. If you don't know your Login or password for the account, find the login block and under it should say something like "lost password, click here". They will send you a replacement temporary password. If the site is used all the time, click the "stay logged in" box. Their computer is recognizing your computer through a "cookie", a registered token. If you don't know the file where your cookies are, type "finding cookies" in the search box of your computer. I will tell you that it can sometimes be a chore to find the exact one because it may not be something you would recognize.