I assume you are omitting the < at start of each tag for this post.
If you are getting cannot open page errors this sounds like you have incorrectly entered the file name or path.
File names are case sensitive. If you called something Myfile.htm then call it as myfile.htm it wont load. Also a common mistake is to forget which extension you are using, are you using .htm or .html ?
Is the frames code page saved in SAME directory path (Folder) as the files you are trying to load? If not you have to enter the proper path eg src=?/htmlcode/filename.htm? in this example it will load a file filename.htm in the folder htmlcode in the main root directory.
Leaving of the leading / you are saying that the file is located in a the folder htmlcode which is located in the same folder as the file its read from.
I prefer to call full paths from root directory because when any files are moved around I don?t have to change any code.
I assume you have a general knowledge of directory (folder) paths, but will give it a very brief mention now. If you still need any help with paths I or someone else can explain better.
From a design point of view Frames are very outdated now for a number of reasons to do with browser compatibility, pages getting trapped in frames and other funny quirks. Personally I think that Frames also look ugly, and make the page feel heavy going.
For small sites with not many pages using a table will be better, however if you are producing hundreds of pages and then want to change the menu its going to be a nightmare.!
So this is where PHP comes in. This not as hard as it may seem you still can use 99.9% of your site in HTML, a simplified way to use php is :
$include_path = dirname(__FILE__);
</td><td> your html code as normal here</td>
now all you have to do is save it as .php instead of html and all you have to do is create 1 html code for your menu. Please note you will not have to include any <html tags etc, as the php will paste into the table.
Anyway I?m getting side tracked now but this is a good option to take and is worthwhile and may give others looking an idea.
ANYWAY if you still have problems with your frames and it is not a path issue dont hesitate in asking