Macros WORD VBA

You need to write a macro for MS Word 2007. The macro task is to process the text by inserting a certain symbol next to each letter and format it in a certain way (inserted symbol). Also, a variable should be specified in which you can specify what percentage of text should be processed, for example, indicated 25 - then 25% of the total text will be processed. In addition, the processing should end with a decrease in the number of inserted symbols. The processing should also begin at the end of the document. An example of the processed document is attached. The same effect must be achieved.