I try not to confuse you... Because you didn’t mention about
Roth IRA, I presume you meant traditional IRA, I won’t discuss Roth IRA below…


First, IRA means "Individual Retirement Account". It cannot have two
owners in one account. So there is NO NO about “simply adding your name
to your husband's IRA”...


Second, the IRA contribution limit.The general limit is the smaller of “$4,000” or “your
taxable compensation for the year”. So if you are single and you are not
working, you cannot contribute a dime.

But, you are married and you file a joint return with your
husband.  The “spousal IRA limit” allows
you to contribute to your IRA on the smaller of “$4,000” or “the total
compensation minus your husband’s traditional IRA contribution and ROTH IRA
contribution.”

For example, your husband’s annual salary is $50,000, his
IRA contribution is 4,000. and he also contributed to his ROTH IRA 4,000, then
the amount is 42,000. That means you can contribute $4,000 to your traditional
IRA…
In this example, you can open  your own IRA account and
contribute $4k, and your husband’s IRA account can have $4K,

If your husband’s annual income is only $7,000, he already
contribute $4,000 to his IRA. Even he doesn’t have a ROTH IRA, you only allow
to contribute $3,000 to your IRA… (the lesser of “$4,000” or “$7,000 minus
$4,000” )

 
Ok, the next is to figure out how much you can deduct on
your tax return. Most people got confused and made false statements on “deductible
contribution” and “contribution limit”. You can make the contribution up to
your “contribution limit” to accumulate tax-free benefit. But you two might not
be able to deduct 100% of the contribution amount on your annual return…
 

In your case, if your husband is also covered by an employer
retirement play (say, 401K), and the modified adjusted gross income is more
than $70k,  you better study hard on IRS Publication 590. page 15 , table 1-2
    http://www.irs.gov/pub/irs-pdf/p590.pdf 
Publication 590 is the “bible’ of IRA….