Hello,
You have a couple of options.
1) If you are installing a fresh installation of DNN and are just wanting to transfer across your modules, skins, and content you can create a portal template on your localhost install and then load the portal template on your live website. - I've created a video tutorial on how to do this here:
Configuring DotNetNuke before Installation - It's on video 2
You can also view this forum post:
How to export data from a localhost install to a live website in DotNetNuke
2) If you are wanting to synchronise your data from your live website with your laptop permanently it becomes more complicated. - Basically you have to create a backup of the database from your localhost install and then FTP the backup database and all of the files from your DNN localhost install over the top of your live website. You will have to enquire with your hosting provider how to restore a backed up database, usually all you have to do is FTP the backup database into a folder on your live website and your website will automatically install the backed up database.
You will reverse this method to transfer the data from the live website to the localhost website.
Transferring data to a live website in this way on a regular basis could raise a few problems for the users of your website. - EG. You will need to prevent access to your website while you are restoring the backup and transferring across all of the files to prevent any errors.
I avoid this method as I try to keep my websites online for as long as possible.
Once a website is up and running I use the following methods to add new content to the website.
1) On a localhost install, add the module to a page and add the content you require - Go to the module settings menu and use the export data function. - Copy this file that has been created and FTP it to the live website - Install the same module to a page on your live website and then select import data and select the data file that you have just uploaded via FTP. Voila! - all of your content has now been transferred.
2) If I am thinking of adding a new module I test it first in a localhost install to ensure it is compatible with the current live installation. - I then add it direct to the website and add the content direct to the live website.
3) Whenever adding text content to a live website I will always create the text in Word to spell check and then copy across that text to the live website.
4) If you are worried about rollback on a live website then make sure you backup your database and files before adding any changes to the live website, at least then if you make any mistakes you can restore the backup.
5) Create any new content in a hidden administrator area first to check that it is all correctly working.
I would recommend that whichever method you choose that you fully test it before applying it to a live busy website so that you are sure that your method works 100% and creates minimal down time for the visitors to your website.
I hope this provides a few pointers, thanks.