Our client srequest to add title_linha_ip45. I've already create the index linha_ip45 (indexed attributes: ip45), metadata linha_ip45 and I edit the form and add a input to add the linha_ip45 value bue the value isn't save.
I've read that I've to perform a update to the catalog, it's the only think I've to do to be able to save the value of this new fieldIndex?
Your question, your text, your text is more than incomplete.
Form data is not automatically saved somehow and not indexed at all.
If you have a content-types (for whatever) then you must define a new field in your schema (either in Dexterity or Archetypes - you did not mentioned anything....). Additional indexes are usually defined inside the catalog.xml of your Generic Setup profile.
...so it is completely unclear what you are doing or asking in particular.
And I need to add a new field "ip45".. thats a category of products,
I'm new to plone, the web developer of my company just left and didn't give any kind of knowledge to no one.. step by step I'm starting to understand a litlle of the plone structure but its kind weird and a lot diferent of the usual php sites.
Looks like you're working in an Archetypes based system. The form you're working in is just a view on a content type. If you don't add the field to the content type, nothing will be saved.
The alternative is to hire somebody who has the required expertise. Still cheaper than rebuilding the site, probably. There's plenty of people who remember how to work with Archetypes, and most are on this forum.
Depending on the application you could use Plomino or rapido. If you don't care where you store the information and you don't want it to "act" like content but you want an easy way to have control of the look and feel of the forms and interaction then this is a good way. Rapido is only for plone 5 and is more developer focused.