You can reach the search/replace dialog via menu item Edit - Search and Edit - Replace, or you can use the key commands Ctrl-QF ("find") and Ctrl-QA.
Case sensitive
"Case sensitive" means that the search function makes a difference between capital and lowercase letters.
Search or replace several words
The search algorithm works line-orientated. If you enter an expression containing two words or more, and the second word is in the next line, you won't find the expression. (I will improve that in a later version.)
How to enter special characters into the edit field
To enter an arbitrary ASCII character which is not available on the keyboard, write a hash # (double cross), followed by three digits for the ASCII decimal code. If the ASCII code has only one or two digits, then use zero characters: #002. Enterig ^ and B (^B) accesses the same character in Wordstar notation.
If the hash sign # is not followed by three digits, the string is treated normally.
Anyway, you can use the clipboard to copy these special characters from the editor
into the clipboard (Ctrl-Ins) and then to the edit field of the search/replace
dialog (Shift-Ins).