Hi Vicky, I have found this info for you. I don't do Red days myself. I'm sure some of the followers of the Red plan may be able to add to this or even explain it a little better, but I hope it goes someway to help you.

The basic rules of Original Plan/Red Days
Free foods include:
All lean red meats
All lean poultry and pork – including bacon
Fresh fish/seafood
Eggs
Quorn mince/Quorn pieces
Vegetables*
Fruit
Some fat free yogurts (ie most Mullerlights)
These are the main foods that can be eaten freely, meaning in UNLIMITED AMOUNTS. As with Extra Easy, the proviso is that you do not add fat to these foods – during cooking or afterwards. Always trim off all visible fat prior to cooking.
* A small exception here. There are some starchy vegetables which cannot be eaten freely, including potatoes, sweet potatoes, yams, sweetcorn and parsnips.
As you can see from above, Red Days mean meat. You are sacrificing pulses, potatoes, pasta and rice as Free Foods. But even though you are making this sacrifice, you receive a reward in the form of DOUBLE Healthy Extras! For example, you can have four Alpen Light bars instead of two. You can have two servings of Nimble bread instead on one – meaning you could have toast for breakfast and a sandwich later in the day. Or, you could have Weetabix in the morning, and a Kelloggs Fibre Plus bar with a cuppa in the evening. The same rule applies to Healthy Extra A choices (dairy products). This could mean a full 250ml of semi skimmed at breakfast, with 45g of mozzarella melted over some grilled chicken and bacon at dinner. There are lots of ways to use your extra Extras to perk up your menu throughout the day. If bread/cereals aren’t your thing, you can have MEASURED AMOUNTS of potatoes/pulses instead. For example, with your huge steak and salad, you could have a jacket potato weighing 227g. Or with your morning fry, you could add 142g of baked beans.
Admittedly, when you begin in introduce the concept of weighing items that you are used to eating in unlimited amounts, it does begin to feel restrictive. But bear in mind, this plan will more often than not accelerate your weightloss – so at least give it a go. Soon, weighing will become a natural thing.
As with Extra Easy, you are allowed between 5 – 15 syns a day.