Mail Merge is a valuable feature in Microsoft Word that helps you save time when handling various types of inserting lists into a fixed template such as invitations, announcements, thank-you letters, report cards, and more.
Although this feature is very useful, many users are unaware of or overlook the Mail Merge feature. Refer to the article below to learn how to perform mail merge in Word 2007.
First, you need to have a pre-created template Word file to insert information. Then, follow these steps:
Step 1: Open the template Word file, select the Mailings tab -> Start Mail Merge -> Step by Step Mail Merge Wizard.

Step 2: The Mail Merge appears on the right side of Word, choose Letters in Select document type and select Next: Starting document.

Step 3: Continue selecting Use the current document and choose Next: Select recipients.

Step 4: In Select recipients, choose Use an existing list if the list is available, or you can select Type a new list to create a new list. Then, press Next: Write your letter.

Step 5: In the Select Data Source dialog box, choose the available list and click Open.

Step 6: Choose the sheet containing the data you want to use. For example, in this Excel file, Sheet1 contains the data, so choose Sheet1. Then, click OK.

Step 7: In the Mail Merge Recipients dialog box, select the data to insert by checking the checkboxes next to the data. If you want to insert all, check the box next to Data Source.
After selecting, click OK.

Step 8: Select Next: Write your letter.

Step 9: In the next step, place the cursor where you want to insert the data, then click on More items.

Step 10: A dialog box Insert Merge Field will appear, choose the correct data field next to the cursor and click Insert to insert.

After inserting, click Close to close.

Step 11: Insert all data fields into the existing Word template. Click Next: Preview your letters.

Step 12: Select Next: Complete the merge to finish the merging process.

Step 13: To view all pages after merging, choose Edit individual letters.

Select All -> OK.

Step 14: You can save the file by selecting File -> Save or pressing Ctrl + S, naming the file, and choosing the folder to save it in.
Here is how to use the Mail Merge feature to merge letters in Word 2007. You can use this feature to create files with similar templates. The process is similar for MS Word 2010 and MS Word 2013. Wishing you success!
