Problem with Yahoo Hosting/Zen-Cart - .htaccess

Hello everyone,
I am new to Zen-Cart and trying to upload the files to my server. However, the host (Yahoo) doesn't allow uploading .htaccess files. I don't know what is .htaccess files, but I know that I can't upload them.
Will I be able to get Zen-Cart to work? And what are the disadvantages of not having these files uploaded?

I can't change my host at the moment, so I must work around this. Will I have to switch to another shopping cart?

Thank you in advance for help.

I'll tell you my experience with yahoo hosting: I installed zencart, and looked perfectly fine after install. Then thankfully directly after install I had a really dumb question for the yahoo folks, and when they found out that I had install it, they had a laundry list of things that would not work:

-Like customers could NOT register and create an account
-Zencart cannot send emails
-Credit cards purchases not secure
-and blah blah blah

So I didn’t believe them, and I carried on with my store, and sure enough, the main one was a major hick-up. No one can create an account or log-into the store… ugghh

They have closed/shut down all kinds of features to ensure that no one installs Zencart in their hosts due to the fact that they have an out of the box store/cart that they sell via their host at a very hefty price.

There maybe round about ways to do it, but I’m sure not techy enough to do it, so I had to change servers to be able to install Zencart stores.

Addie