How to put the link of the file on our another file which will redirect people to my fist file

I had made 2 files of html name are index.html and index2.html respectively. Suppose if I had used the anchor tag in my index.html file to redirect to my index2.html file which contains some sort of information. Than how should I use the anchor tag if both of my file are in the same directory but are on the different folder or the sub folder on the same directory let's suppose the name of the directory be Project and the sub folder for index.html and index2.html be folder1 and folder2 respectively.