If you just want to find a text string, the best tool to use is grep. sed is designed more for modifying strings.
Certain characters such as the slash are considered special by either the shell, the regex engine of the tool you use, or both. In most cases you can escape them by placing a backslash in front of them.
Here are a few useful pages from the Advanced Bash Scripting Guide that may help you. Grep isn't specifically discussed, but most of what you learn can be applied to it.
Here are a few useful bash scripting references:
PS: If you show us the exact command you tried to use, an example of the text you're trying to search through, and the output messages you get, we'll help you come up with a solution. Also, try searching through previous threads on the subject, as this kind of thing comes up often.