Have a look at the Aussie immigration website
Department of Immigration and Citizenship and follow the links through for both yours and your OH's skills/trade to get you started.
I am almost certain you can't do the skills assessment part online yet only the actual skilled visa (175).
I agree with Mrs Keily completely that you should speak to an agent first as regards who should be the main applicant and therefore get their skills assessed. Whomever the main applicant is, you or your husband will automatically be included in the visa along with any children not deemed independant.
Good agents to contact are Ian Harrop & Assoc -
Registered Australian Migration Agents, UK - Ian Harrop and Associates who we used and were absolutely brilliant and Go Matilda who get good feedback on here too. Their MD Alan Collet comes on here now and then to help and advise. Both I believe will offer you a free consultation on the phone.
Good luck
Lyn