Unless you're some sort of computer wizard, it's unlikely that you'll be able to hack your husband's locked computer.
Passwords are created to restrict access to personal files and information, so you only really have two options in order to gain access to your husband's computer.
This one is self explanatory, but there aren't many options available to you. The easiest way to gain access to your husband's locked computer is to find his password.
You could try to guess the password, which is likely to contain words relevant to his life. Perhaps dates of birth, children's names, and special dates are a good place to start.
Administrator access
The only other chance you've got is if an "Administrator" account has been made active on his computer. To see if this is the case, you should reboot the computer and access Safe Mode.
You then need to select the Administrator account if it's available, and from within this account you'll able to change the main account's password.
A word of warning
This is a risky method as it's likely your husband will know you've been messing around with the settings. I would advise that you don't try to access your husband's computer without his knowledge.
Your best bet is to ask him for the password and see what he says. If he refuses to provide you with the password then you can ask him what he's hiding. Bear in mind that he might just prefer to have a private space, and this doesn't necessarily mean he's doing anything that you wouldn't approve of.