To customize the homepage for a specific subsite in SharePoint, try the following steps:

1. Navigate to the subsite
   From the parent site, select the subsite you want to customize.
2. Select the Settings menu option
   Once you have navigated to the subsite, select the Settings menu option located on the ribbon.
3. Select the Site Settings option
   From the Settings menu, select the Site Settings option, which will direct you to the Administration page of the subsite.
4. Select the Look and Feel option
   From the Site Settings page, in the Look and Feel section, select the page the homepage you want to customize.
5. Edit the page as necessary
   Once you select the page, you will be taken to the Design tab. From there, you can add webparts, text, images, and documents to customize your homepage.