Web hosting is basically renting space and bandwidth through a company that has web servers so that you may publish your web site on the internet.

Well generaly you will email everything to them! *joke*

Uploading your site can be done in many ways, but the most popular is via FTP(File Transfer Protocal).

When your hosting account was created, you should have been provided with an FTP account. Using software such as CuteFTP or WS_FTP, you can log into your host. Then, using the program like a normal windows program, you can drag and drop files onto your web host. These files become live online instantaneously.

Some hosts will provide a browser based fle manager that allows you to upload, delete and modify files on your domain. This is usually found in the control panel provided by the hosting company.

Sure, you could do that, but it's not a good idea for several reasons. First, a vast majority of ISPs won't let you legally use a residential cable modem or a DSL line to host a public server. You would have to get a more expensive business package. Second, DSL and cable lines usually have lower upstream bandwidth than downstream bandwidth, so your site may appear to be sluggish under heavy traffic. Third, DSL and cable lines have a much lower reliability than dedicated T1 or better lines. Fourth, you wouldn't have the benefit of data security, data backup, UPS power, or technical support that a host can provide.

There are pros and cons with both options. Larger companies have a better chance of being in business in the long haul, have thier own facilities and large support staffs.

Smaller/newer hosts usually provide better support, are cheaper and will bend over backwads to keep you business.