Yay! You have received your Glam Seamless Color Ring - the best thing to do is go outside! Sunlight is the best lighting for the most accurate color matching. Indoor lighting - whether fluorescent or LED can often lead to an inaccurate understanding of color.
You want to color match to the ends of your hair, this is where the extensions are going to live. Hair - even virgin hair - has various tones and most often your roots will be darker than your ends. Since your extensions will live past your own ends its most important that the color you match to is your ends. This is true for all extension options from tape ins to clips and even the halo, for the most part, your roots will color the top 2 inches of the weft.
All of our hair colors are made with multi-tonal adapting coloring technology - very minute variances in each color allow a shade to match within a range. It is best to purchase two different shades and blend them in this way when it is all installed it will be your perfect custom tone.