Search and replace/insert HTML code into Master File using tags

Hello

I need ideally a formula that can do the following;

Example of the cell A3 tag 1FINDandREPLACE

Step 1: Look within a specified cell (i.e cell A3) and copy the tag in that cell.
Step 2: Search within cell B2 (B2 contains various text that includes the tags).
The tag in cell B2 is then to be replaced with the content from cell B3.

Step 3: Repeat steps 1 & 2 for tags A3 to A9 and MASTER HTML FILE B1 to L1 and more

This is a simple idea, but unfortunately I have not been able to find the code already in the forums that can do this task?

Attached is the problem in the excel file.

I look forward to your suggested formula, or if a formula is not possible, a macro could be used and any suggestions on the macro code would be helpful.

Kind Regards
David