Step 1:  Create/Edit a file .htaccess in the documbent root (public_html / www folder)
of your hosting account and put the code below inside .htaccess file :

#----------------------------------
Options +FollowSymlinks
RewriteEngine on
rewriterule ^old-page.php(.*)$ https://your-new-url.com/new-page.aspx$1 [r=301,nc]
#----------------------------------

Step 2: Replace your page name in last line of above code, 
add your old url first by replacing "old-page.php" and
add new url where you see "https://our-new-url.com/new-page.aspx"

Step 3: Save & upload file into your old hosting server and you done !

Now your old domain name reffer visitors to your new domain name.