ive been using linux for about two weeks now. and im still not very familiar with it. but over the past two weeks linux hasnt been able to connect to my DSL internet. my internet provider is sbc yahoo. i called for support and they were not able to do anything for me. Now ive tried everything to hook up my internet. when im on windows i am able to connect without any problem. but linux is a whole other story. when im on windows my modem (speedstream) has four lights on (power, dsl, ethernet, and activity) when i am on linux it only has two (power, and ethernet). i have no clue what is going on with my computer. so i would really appreciate it if you could help. if you know a number i can call for linux support or etc. i would really appreciate it. if you need any more information concerning my connection or etc. please feel free to ask. thank you.

Use the Search/Search Forums at the top of the forum screen.
Type in
speedstream
and you will get many threads with that word inside the posts.
Try to read them first and to find if a solution is already given.
If not, give more infos about your exact modem type and the connexion to internet (usb or ethernet cable).
I'm not an expert on that matter, but someone surely will be more apt to answer you if you give more infos, after having done some reading first.

I've been using Linux for over ten years now. And I'm still not very familiar with it.
So one nice day Linux did not connect any more?

As you describe it Windows makes PPPoE connection. You could do the same in Linux. You didn't tell us what distro and desktop environment you are using. You may have a GUI tool for this.
Setting up the Speedstream as router would be even better.

What network card you have? Do you get an IP-address from ISP's DHCP-server or do you have to log in at some page with username and password?

What distro are you using? Do you have support for your network card in your kernel or as module? Is the module loaded? What does it tell you when you issue the "dhcpcd eth0" command on console?

Here's few questions for starters.