First draw out the floor plan or the room or area then use laser measure tape or traditional measure tape. Start with measuring wall to walls then add measurements for the doors and windows. Also make sure to photograph the room all the way throughout for future reference when putting the floor plan drawing to scale.

The best starting off software is vectorworks. It’s easy to use and the outcomes provide you everything you need to complete projects. Also, Highly recommend Photoshop and Indesign for portfolio layouts. 

A design concept is a creative idea to showcase something within your design  or to answer the brief requirements in a creative manner. 

The best way to approach any interior design or architectural project brief is to first break down what the brief requirements are. These are usually a set of design objectives you have to achieve within your projects for example if you were designing a cafe or restaurant. There may be X amount of table and seats required or if you were designing a family home. There may be X amount of bedrooms and bathrooms required in the brief. Once you have identified the project's requirements, you move on to apply these requirements in a series of concept plans. In order, to see what layout works best and achieves project requirements.