How to create new group for products in drupal commerce?
I guess you need to create a new product type (since you want to add "parameters", which I assume are "fields") :

/admin/commerce/products/types/add


Then add fields to your new product type (picture, size, screen resolution for phones...), choose chich fields will be used as attributes (like size for shirts), then create products using this new product type, then create a new product display (which is a regular node with a multiple product reference field) for this product type and reference your products with the product reference field on the product display. You can also use an existing product display to display all your types of product (in this case you have to allow the product display's product reference field to reference products of the new product type first).

Note that if you have several attribute fields, you need to create as many products as there is possible combinations. Say you have 3 sizes (S, M, L) and 2 colors (red, blue), you need to create 6 products :


S blue
S red
M blue
M red
L blue
L red


You may consider using Commerce Product Option or similar module for your use case.

It can be confusing at first, but the Drupal Commerce way of dealing with products is really effective.

Good luck

EDIT

To make a field act as an attribute on your add to cart form (i.e shirt sizes : a drop down with XS, S...), you need to define a field on your product type (see my URL), then on the manage field form (admin/commerce/products/types/your_product_type_machine_name/fields/your_field_machine_name), you need to check the checkbox "Enable this field to function as an attribute field on Add to Cart forms".

Then you create your product, one with size S, one with size M, one with size L (so you have 3 products, one per size), on your product display you set up references to the 3 product variations (S, M, L), and there it is, on your product display page you'll find a drop down allowing to choose the size in the add to cart form. When selecting a size, the node fields are refreshed with AJAX (you can see it as an AJAX product selector).

This system allows you to have different SKUs and prices for each variations. Typically, everything that needs to be different across products variations (SKU obviously, but maybe price, maybe the product picture) needs to be represented by a field on the product (each product has its own field value). Everything that is the same across product variations can be represented by a field on the product display (which is common to several products.

See here for official doc.

Hope it helps and sorry for my english, not my first language.