Very first thing is open your cPanel (or plesk)  and look at your error log and see if someone is running a script, it will be obvious, look for strange behavior such as alot of file not founds from one ip or a group of ip's

You may also want to take the site offline if you dont have alot of members or if noone is online now till you get the ip's taken care of 

Then block that IP by using ip deny feature  (make sure it is not your ip first)  There may be several ip you need to block.  This will keep them out a then we can do repairs.

Make sure you have  deny all  set up in your htaccess for both the htaccess and the php ini file.

What is your site url ?

if it is the one in your profile then you have many members online so you prob should not take it offline.   Can you show us a screen shot of the welcome and the members profile?   It would help.

Again, thank you very much.

I called a friend and asked him to give a look at my website. He looked and told me he saw nothing like that on the website.

I did not believe him because i was looking directly at this link on the website. I called another person to look. he told me the same thing that he could not see any such link.

I left my computer and went out to cafe. i looked at my website but the link was not there.

Why was it appearing on my computer?

This is what i later discovered:

The link that appeared on my site was inserted there through a certain website that looks more like a google chrome but it was not google chrome it was a fake. 

Yes, this was how i discovered it:

I clicked google chrome again and when it opened i saw that the website that opened was actually not google chrome. It was a fake and under it was a big advertisement banner.

I copied the name and searched the net and discovered that a lot of people have got different experience about it. I read some tutorials on how to get rid of it and I am glad i was able to get rid of this monster. 

Again, thank you all for your kind support.