Place Various Lines Of Text Into Textbox1 From A List Of Information?

I have a forum with three text boxes and one button. I need to place various lines of text into textbox1 from a list of information.The list contains hash codes and user ID and various ofter pieces of information without spaces or punctuation. Most of the information I don't need. However, I do need the first 25-30 characters and last 25-30 characters from each text.

Lets say this is the text:

Simmon_unit32=sub4g36ff&product= shipment29664KL49Loc% 6679KM94

I need to place the above line of text into textbox1 (this I'm doing through cut and past, so not a problem). Then, click button1 and have everything before "&product=" display in textbox2 and everything after "Loc%" display in textbox3. The line of text will usually not be the same number of characters. There may be 10 characters before and after those words of 50 characters before and after those two words. So, how do I create a substring or loop (or something) that will read the line of text and display what I need in textbox1 and textbox2, regardless of the amount of characters in the line of text?

[edit]Unfortunately there are multiple & and % signs in the texts. In fact, there will most likely be an & sign somewhere before "&product=". However, "&product=" only shows up once. As far as the % sign goes. There will be 3 or 4 of them in the text. To make matters more difficult, "Loc%" also shows up multiple times in the text. But, I only need the information that displays after the very last % sign to appear in textbox3, if that helps.I'm using visual basic 2008, in a Windows forms Application.