How do we me and my husband apply for JOINT bankruptsy?

If you are in the US, you didn't specify a state, than you can buy a self-help kit online to help guide you through the process.  You can also go the the nearest district court in your area and they should have all the forms there for free.  You can even try legal aid or if there is a law school nearby where you live try their free/low cost clinic.  Obviously, if you can afford it, the preferable thing is to hire a bankruptcy attorney to file for you.  At any rate, the forms are set up for individual or joint filing.

As for whether or not you should file jointly, it is usually preferable for both spouses to file for a joint bankruptcy for the following reasons:

          Bankruptcy costs - the costs that debtors have to pay for a bankruptcy are about the same for a joint case as they are for an individual case.  If your spouse files at a later time, you will be paying the costs for two cases;

          Joint debts - if your spouse does not join in your bankruptcy and you and your spouse share responsibility for payments on the same debts, your spouse will remain liable for the joint debt and may continue to be pursued by creditors;

          Efficiency - the amount of work performed in filing joint schedules, statements and other documents in a bankruptcy case will be reduced if you and your spouse file a joint bankruptcy.

There are, however, several valid reasons for not filing for joint bankruptcy.  One obvious reason is that your spouse does not want to participate in a bankruptcy.  But, there are a few situations when a joint bankruptcy may be a bad idea or just isn't available:

          Your spouse is barred from filing because of a prior bankruptcy;

          You and your spouse jointly own property that is in excess of federal exemption levels is protected from creditors by broader exemptions under state law;

          If you are pursuing a Chapter 7 bankruptcy, your spouse is barred from filing by some likely objection to discharge;

          If you are pursing a Chapter 13 bankruptcy, your spouse has a large priority debt, has debt above the Chapter 13 debt limits or has some other debt problem that makes a joint bankruptcy impossible;

           In some community property states, it is not necessary for the other spouse to join in the bankruptcy because nearly all community debts and community property will be affected by the individual spouse's bankruptcy

There are other considerations with respect to non-joint debts and exemptions.  To determine if you and your spouse should file for joint bankruptcy, it is strongly suggested that you consult with an attorney.  Even if you decide not to hire him and have him do the actual filing, at least meet for an initial consultation about whether or not you should file jointly.