Is it ok to write like this?
<a href="add-lead-new.php" target="rightframe"><input type="button" value="New booking" /></a>
The link should look like a button but it should open in the right part of the page. If its wrong, is there any other way to do it?
The above code works fine. i just don't know if its the correct way to do it.
No, this is not allowed according to the HTML5 specification.
<button>element is considered "interactive content".
<a>element must contain "no interactive content".
The button will probably show up, but since you're violating the specification it may not behave as you want. You should avoid doing this.
The most reliable to way to make a button bring the user to a page is to create a
targets that page, and make the button submit that form.
<form action="add-lead-new.php"><input type="submit" value="New Booking" /></form>
<input type="button" value="New booking" onclick="self.frames['rightframe'].location.href='add-lead-new.php'"/>
would be ok
It's better to just use CSS, but if you're really stuck on using a physical button, you can create a dummy form with no data:
<form action="href"><input type="submit" value="Click Here" /></form>
Yours is working but this is better,
<input type="button" value="New booking" onClick="top.frames['rightframe'].src='add-lead-new.php'" />