Allow users to sort images based on category selected (paperclip gem) - Rails

Currently my home page (index.html.erb) shows all the user images loaded within the past 24 hours, which is part of posts. However I would like to add a form that allows the user to sort images based on their category and upload date. (For example images with the category music, uploaded within the past month) I understand how to query the database but I dont know how to take the user input. When I create a form, suing simple form: <%= simple_form_for @posts do |f| %>, it throws an error, saying I cannot use an object. Ive thought about ajax but it doesnt seem to work well with the paperclip gem, plus I rather get it done on the backend. I hope my issue well enough. If not feel free to comment as I will be around to respond. Thanks in advance.

Post Controller:
 def index  
 @posts = Post.all.where(created_at:(Time.now - 1.day)..Time.now)
 end

Schema for Post table:

create_table "posts", force: :cascade do |t|
t.string   "title"
t.string   "instagram"
t.text     "description"
t.datetime "created_at",                            null: false
t.datetime "updated_at",                            null: false
t.integer  "user_id"
t.string   "image_file_name"
t.string   "image_content_type"
t.integer  "image_file_size"
t.datetime "image_updated_at"

via Chebli Mohamed