I think you have to look at it from 2 different viewpoints
1. Setting up and configuring your website, on the server
2. Creating your website with Umbraco
Regarding #1: Umbraco is actually quite easy to set up and configure, if you are experienced in setting up and configuring websites using IIS and MS SQL server. You just have create your website directory on the server, copy the installation files from codeplex to this directory, create the website in IIS using the new directory as the root folder of your directory, edit the acl's on the directory to allow the network service to modify files in certain directories, set up an empty database in SQL Server, and edit the web.config to use this DB. When that's done Umbraco will take care of the rest for you first time you visit the website.
If you don't know what all this means you're probably better of buying dedicated Umbraco website hosting. Look in the "
Hosting Provider Forum" to se suggestions on which providers to use.
Regarding #2: Your css, html and javascript knowledge will be of great use. Ysing templates you will be able to create exactly the (X)HTML output you need, and maintaining css, and uploading images and javascript files to your site is very straightforward.
If you don't know XSLT, XSLT "programming", and understanding how to use XSLT+Macros to output stuff like menu lists and stuff like that will probably be were you will experience the steepest learning curve. I'll recommend you install one of the website packages available when right clicking "Macros" in the developer section. these packages comes with a number of good examples to learn from.
Regards
.Hauge
Do what you want with Umbraco