How to change the color and content in the Toolbar?

Hi all. Do not judge a stupid question, I recently started to look into Android Studio and Java. Like all do as they say, and not leave a stone flower.
Add the toolbar, it is gray, although the topic written by others(in other places colorPrimary works). And it says "android... Toolbar". If I understand correctly, should be the name of the app? In short, I can't add anything inside and can't change the color. Why? I'm sure that the answer is a very simple, somewhere I have something written, but can not understand where. Help, please.

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
 package="com.eremeeva.dietcalculator" >

<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme"
tools:ignore="GoogleAppIndexingWarning">

 <activity android:name=".MainActivity" >
<intent-filter>
 <action android:name="android.intent.action.MAIN" />

 <category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

</application>

</manifest>

toolbar.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.Toolbar
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="parent"
android:layout_height="wrap content"
android:id="@+id/my_toolbar"
android:minHeight="?attr/actionBarSize"
 android:background="@color/colorPrimary" />

styles.xml

<resources>

 <!-- Base application theme. -->
 <style name="AppTheme" parent="Theme.MaterialComponents.Light.NoActionBar">
 <!-- Customize your theme here. -->
 <item name="colorPrimary">@color/colorPrimary</item>
 <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
 <item name="colorAccent">@color/colorAccent</item>
</style>



</resources>

colors.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
 <color name="colorPrimary">#8F00AD</color>
 <color name="colorPrimaryDark">#8F00AD</color>
 <color name="colorAccent">#D81B60</color>
</resources>