Joomla website conversion

I have a not for profit website www.swimhistory.org. I am doing a PhD i n sports history, and this site is the result of my research. Its a mess, and I need to convert the data onto a Joomla site.
I have had a few design concepts done, and have a spreadsheet of the menu layout. I don't like boxy website - rectangular box due to fixed width - like the attached layout I got from another developer. I also include my ideas on a menu structure.
I made the current site, so I have some idea of website management. But I need a searchable Joomla site - home page and two data pages for articles, two and three column, and I will do the rest. You can obviously use an existing template, so it won't be too much work.