now you can actually create tags

app/controllers/tags_controller.rb

@@ -0,0 +1,48 @@
+class TagsController < ApplicationController
+  allow_unauthenticated_access only: %i[ index show ]
+  before_action :set_tag, only: %i[ show edit update destroy ]
+  def index
+    @tags = Tag.all
+  end
+
+  def show
+  end
+
+  def new
+    @tag = Tag.new
+  end
+
+  def create
+    @tag = Tag.new(tag_params)
+    if @tag.save
+      redirect_to @tag
+    else
+      render :new, status: :unprocessable_entity
+    end
+  end
+
+  def edit
+  end
+
+  def update
+    if @tag.update(tag_params)
+      redirect_to @tag
+    else
+      render :edit, status: :unprocessable_entity
+    end
+  end
+
+  def destroy
+    @tag.destroy
+    redirect_to tags_path
+  end
+
+  private
+    def set_tag
+      @tag = Tag.find(params[:id])
+    end
+
+    def tag_params
+      params.expect(tag: [ :name ])
+    end
+end